Rotary actuators find widespread use in connection with fluid flow control valves of varying types for purposes of automating valve control or simplifying the control of inaccessible or remote valves. Since neither the rotary actuators nor the valves commonly employed in such circumstances are specifically designed for coupling with one another, a special bracketing system must be employed to join the valve and actuator bodies and couple the actuator output shaft with the valve stem or other valve actuating member. For the same reason, an inherent problem exists in obtaining and maintaining correct alignment between the actuator output member and the valve stem over the course of their coupled operation. As a result of this problem, conventional bracketing systems commonly provide a relatively extended separation between the valve and actuator for accommodating the misalignment thereof which may be expected to occur over the course of their coupled operation and thereby to minimize the effects of potentially destructive non-torsional reactive loads on the valve stem resulting from the valve actuation forces generated by the actuator. As will be recognized, such bracket arrangements do not solve the indicated problem but at best merely accommodate it. Further, the extended nature of such bracket arrangements significantly increases the space requirements for valve and actuator couplings.
One practical solution to these problems is disclosed in U.S. Pat. No. 4,719,939, by the same inventor as the present invention and commonly assigned herewith to Conbraco Industries, Inc., of Matthews, N.C., which provides an apparatus for coupling a valve and an actuator compactly in close positive alignment with one another while protecting the valve stem or like actuating member from reactive loads generated by valve actuation forces. Basically, this close coupling apparatus is adapted for use with a valve of the type having a valve body with a gland arrangement rotatably supporting a valve stem for actuating opening and closing movement of the valve and a rotary actuator of the type having an actuator body rotatably supporting an output shaft. A drive arrangement is provided for establishing coaxial drive connection of the valve stem and the actuator output shaft for controlling the opening and closing movement of the valve. A bracket arrangement substantially rigidly connects the valve body and the actuator body, the bracket arrangement having an opening which conforms to the gland arrangement for receiving the gland arrangement to apply reactive loads generated by valve actuation forces to the gland arrangement. In such manner, essentially only torsional actuation forces are applied to the valve stem. This valve-actuator coupling apparatus has been reasonably well received commercially. However, one potential drawback of the apparatus is that the gland arrangement of the valve is inaccessible once the valve and the actuator are coupled. Thus, if adjustment of the gland arrangement subsequently becomes necessary, the coupling apparatus must be disassembled.